Think about this

ok so this is... yeah the picture explains it
the 10 tailed beast, Jubi

It ravaged the land when the Sage of the Six Paths wasn't.. the sage of the six paths.. just a sage

somehow he was able to create a sealing jutsu and sealed the 10 tailed Jubi to himself making him the first Jinchuuriki

as you can see from the picture that Jubi has a Rinnegan and Sharingan combination eye

this got me to thinking...

The sage had rinnegan when he was a legend.. which means that he probably didn't have it before he became the 10 tail jinchuuriki... the Jubi must have gave it to him..

Now we know that the Sage had 2 sons

1 with the sages eyes, chakra, and spiritual powers

the other with his body, willpower, and physical powers

the Brother with the sage eyes had some of the Jubi's power within him and was the ancestor of the Uchiha

Now the Sharingan is (probably) a mutation of the rinnegan that formed it into the tomoe

It is said that Byakugan is the ancester eye kekkei genkai to the sharingan which could explain what happened to the eye color in between the rinnegan becoming the sharingan

Madara and his brother were the first Uchiha to gain the Mangekyou which takes the tomoe and expands them into whatever

Now if we take the entire Doujutsu field into a timeline it would be

Rinnegan~Byakugan~Sharingan~Mangekyou Sharingan

Here is what i'm getting at

All of these eye kekkei genkai came from the Sage's eldest son that had the Rinnegan,
He got the Rinnegan from his father, the Sage of the Six Paths, who (probably) got it from the Jubi..

If you can figure this out then good for you but for those who can't..

This all shows that,

All Doujutsu (eye kekkei genkai) are really the eyes (and powers) of the 10 tailed Jubi

this is just my opinion though..

Tell me what you think about this?

IN FACT

If you think about it further

All Kekkei Genkai are from the powers of the 10 tailed Jubi

It is shown that Jinchuuriki can use advanced elemental jutsu because of their beasts (ex. 4 tails uses Lava, 5 tails uses Steam, and 6 tails uses Bubble) which shows that the 10 tailed Jubi (since it was all 9 tailed beasts put together) had the ability to use Massive Advanced Elements against anything it faced.

The only other way to have an advanced elemental would be to have a Kekkei Genkai.. Sasuke has shown that any kekkei genkai can use advanced elemental jutsu by him using Blaze Release jutsu..

To prove my point.. lets go back to the 2 Sage Brothers

The Younger Brother with the body, willpower, and physical power became the ancestor to the Senju clan..

And The first hokage (Senju) had the wood kekkei genkai that controlled the tailed beasts

The wood kekkei genkai that controled the beasts
and
The Eternal Mangekyou Sharingan that controled the beasts

The younger brother family
and
The elder brother family

Each was given a bit of the Jubi's powers

the Sage's (and Jubi's) Yin and Yang were split between the two

this is (probably) why the Sage chose the younger brother................. he chose the Yang

hhhhmmmmm

I know... i went on a rant...
feel better now

hhhmmm means I'm thinking about it lol

I know

just had a major brainstorm after i read more of the manga

ok here is my brain storm what if Jashin...... is the 10 tails????????

Hiden joinned Akatsuki for Religious resons
Akatsuki wants to recreate the 10 tails
the 10 tails was defeated by the 6 path sage
the 6 path sage was worshiped as a god for defeating the 10 tails

hsence 6 path is good god, Jashin is evil god

But isn't Jashin like a shinigami? he's like a death god.The wikia said Jubi had the shape of Kyuubi.But if Jashin is the ten tails,then if he's kinda like the death god how did he get the rinnegan and sharingan? also if Jubi the ten tailed beast is evil, why would he give the six path the Rinnegan? how come the combinated eye doesn't include the Byakugan?

A) How could it include all 3?

B) No Jashin is not like a Shinigami, a shinigami is the god of death, the Jashin is the god of evil hearts

C) We don't know how he got rinngan and sharingan...... for all we know it could be a genjutsu, or it could be the origin of how the 6 path sage gainned the bloodline to start with.... we willl have to wait and see

D) He didn't he battled the 6 path sage and lost big time, and was sealled into his body and later divided into the 9 demons, and his body was sealled in the moon

E) All we know is the shape of the shadow which looks like the fox..... and we do not know Jashin's shape